Conventionally, there is a method of judging whether the mobile device is housed in a trouser pocket or in a chest pocket, using acceleration, angle speed and angle, and so on detected by an acceleration sensor and a gyroscope that are included in the mobile device (for example, see Non Patent Literature 1). FIG. 21 is a diagram showing an example of a display screen of a system disclosed in Non Patent Literature 1.
FIG. 21 is a graph indicating a temporal change in tilt angle detected by the gyroscope included in the mobile device carried by a walking user. Since the mobile device carried by the user oscillates along with walking, it is possible to observe that an oscillation having a predetermined angle is being detected. On the other hand, in terms of oscillation level (here, angle size), it can be observed that: the oscillation is large when the mobile device is in the trouser pocket because it is significantly influenced by a foot that steps forward, while on the other hand the oscillation is small when the mobile device is in the chest pocket. Thus, the system disclosed in Non Patent Literature 1 judges where the mobile device is located, using oscillation level that varies depending on where the mobile device is located.